Husqvarna 578931605 Lawn & Garden Equipment Fuel Tank Cap Genuine Original Equipment Manufacturer (OEM) Part

What It Is

This is a genuine OEM fuel tank cap for Husqvarna lawn and garden equipment, designed to seal the fuel tank opening on compatible walk-behind mowers, riding mowers, and zero-turn models. It prevents fuel leaks, evaporation, and debris entry.

Fitment & Compatibility

• Check model number: This cap fits specific Husqvarna models (e.g., LTH, YTH, Z series). Verify your machine’s model number against Husqvarna’s parts lookup or the old cap’s part number.
• OEM vs aftermarket: This is a genuine Husqvarna part (578931605). Aftermarket caps may look similar but can have different thread pitch or venting, leading to poor seal or fuel system issues.
• Measurement: Cap diameter is ~1.5 inches (38mm) with a standard 2-start thread. Measure your old cap’s outer diameter and thread count to confirm.
• Not universal: Will not fit most Craftsman, John Deere, or Toro models unless they share a Husqvarna-sourced tank.

Key Things to Know

• Simple installation: No tools required—just twist off the old cap and screw on the new one. Hand-tighten until snug; overtightening can crack the plastic.
• Vented design: This cap has a built-in vent to prevent vacuum lock in the fuel tank. A non-vented cap can cause stalling or fuel starvation.
• Durability: Genuine OEM plastic resists UV and fuel degradation better than many cheap aftermarket caps, which may warp or crack within a season.
• Common gotcha: If your mower runs rough or stalls after replacing the cap, check if the vent is clogged. Clean the vent hole with a pin or replace the cap if needed.

Should You Buy It

Buy this if you need a direct, reliable replacement for a lost, cracked, or leaking fuel cap on a compatible Husqvarna mower. The $9.99 price is fair for OEM quality, and the simple swap makes it a quick fix. Skip it if you have a different brand—measure first or look up your model to avoid returns.